kernel panic: audit: out of memory in audit_log_start

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: bee46b30 Add linux-next specific files for 20200221
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=110103ede00000
kernel config: https://syzkaller.appspot.com/x/.config?x=10693880b4976691
dashboard link: https://syzkaller.appspot.com/bug?extid=36717350cc5f212a8299
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [epa...@redhat.com linux...@redhat.com linux-...@vger.kernel.org pa...@paul-moore.com]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+367173...@syzkaller.appspotmail.com

R13: 00000000000008e1 R14: 00000000004cb435 R15: 0000000000000004
audit: audit_lost=1 audit_rate_limit=0 audit_backlog_limit=64
Kernel panic - not syncing: audit: out of memory in audit_log_start
CPU: 1 PID: 14040 Comm: syz-executor.4 Not tainted 5.6.0-rc2-next-20200221-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x197/0x210 lib/dump_stack.c:118
panic+0x2e3/0x75c kernel/panic.c:221
audit_panic.cold+0x32/0x32 kernel/audit.c:307
audit_log_lost kernel/audit.c:377 [inline]
audit_log_lost+0x8b/0x180 kernel/audit.c:349
audit_log_start kernel/audit.c:1796 [inline]
audit_log_start+0x5ca/0x7a0 kernel/audit.c:1745
audit_log_config_change+0x60/0xf0 kernel/audit.c:387
audit_do_config_change+0xe4/0x100 kernel/audit.c:412
audit_set_enabled+0x3b/0x90 kernel/audit.c:448
audit_receive_msg+0x14e4/0x28b0 kernel/audit.c:1216
audit_receive+0x114/0x230 kernel/audit.c:1513
netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
netlink_unicast+0x59e/0x7e0 net/netlink/af_netlink.c:1328
netlink_sendmsg+0x91c/0xea0 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:672
____sys_sendmsg+0x753/0x880 net/socket.c:2343
___sys_sendmsg+0x100/0x170 net/socket.c:2397
__sys_sendmsg+0x105/0x1d0 net/socket.c:2430
__do_sys_sendmsg net/socket.c:2439 [inline]
__se_sys_sendmsg net/socket.c:2437 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2437
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c429
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fda293e6c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fda293e76d4 RCX: 000000000045c429
RDX: 0000000000000000 RSI: 0000000020000dc0 RDI: 0000000000000004
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005
R13: 00000000000008e1 R14: 00000000004cb435 R15: 0000000000000004
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[Dmitry Vyukov]

#syz dup: kernel panic: audit: backlog limit exceeded

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